The present invention relates to a novel immunotherapeutic agent for tumors.
Recently, attempts have been extensively made to extract components effective for remedy of cancer from cell body of various bacteria and bacerial products. Particularly, trials have been vigorously made to obtain carcinostatic agents with less toxicity by extracting components having carcinostatic activity from cell body of mycobacteria.
Furthermore, clinical researches for remedy of cancer have been vigorously made by using components of BCG cell body or cell body of other mycobacteria as immunotherapeutic agents for various cancers of animals. However, BCG cell body contains components causing side effects as well as effective components, and increase in administration of the cell body per se is very dangerous. Therefore, it has been desired to develop immunotherapeutic agents by removing components causing side effects from the cell body and selectively extracting effective components alone or promoting the activity of effective components by some treatment or other. Thus, there have been developed a cellular wall skeleton component of BCG (See Japanese Patent Application laid open to public under No. 28813/1979), muramyl dipeptide (See Japanese Patent Application laid open to public under Nos. 156812/1977 and 98922/1978), and a glycolipid containing long-chain fatty acid in waxy substance D (See Japanese Patent Application laid open to public under Nos. 3514/1978 and 28830/1979).
It is a primary object of the present invention to provide an effective immunotherapeutic agent for tumors.
Another object of the present invention is to provide an immunotherapeutic agent for tumors which has no side effect.
The inventor found that when young and weak cell body of human tubercle bacillus, Mycobacterium tubercurosis strain Aoyama B or Mycobacterium tubercurosis strain H.sub.37 R.sub.v, is extracted with hot water and the recovered lipopolysaccharide component is purified by fractional purification, lipoarabinomannan having an anti-tumor activity and no side effect can be obtained. The inventor further found that when this lipoarabinomannan or lipid-free arabinomannan obtained by removing fatty acids from this lipoarabinomannan by saponification is chemically modified with a fatty acid, there is obtained chemically modified lipoarabinomannan which is comparable or superior to lipoarabinomannan extracted and purified from cell body in the anti-tumor activity and has no side effect.